1. Field of the Invention
The present invention relates to a technique of winding, for example, photographic film by a predetermined amount that corresponds to, for example, one frame and then stopping it, and in particular to a technique of controlling the stop position of photographic film accurately. The present invention relates to an apparatus having a drive control device that can control the stopping of a moving member accurately.
2. Description of the Prior Art
In photographing with a camera, to make efficient use of photographic film, it is desirable that the film be transported with a minimum interval left between two consecutive already-exposed frames. To achieve this, it is essential to control the stopping of a motor accurately enough to allow the film, which is wound by the motor, to stop exactly in a desired position. Conventionally, the stopping of film winding is controlled by stopping the motor by applying braking or a reverse current thereto a predetermined period of time (or distance) before the position in which the film is expected to stop. This permits the motor to stop relatively quickly.
However, the amount of rotation that a motor makes while its rotation speed drops from a particular level to zero varies from motor to motor according to the inertia and other characteristics thereof, and therefore, if the time at which braking or a reverse current starts being applied is determined uniformly, the film may stop in varying positions from camera to camera, causing each camera to use a different proportion of the film per exposure. This leads to a serious problem in particular in arrangements where such a difference is accumulated every time the film is wound. In the first place, it is difficult in general to stop a motor exactly in a desired position with a simple structure, and this is true not only with cases where the stopping of film winding is controlled but also with any case where the driving of a motor is controlled in some way.